Hydrotreating catalyst for hydrocarbon oil and method for producing same, and hydrocarbon oil hydrotreating method using same

ABSTRACT

Provided are: a hydrotreating catalyst for hydrocarbon oil having a hydrodesulfurization activity additionally improved by: simultaneously and continuously adding an aqueous solution of an acidic compound containing titanium and an aqueous solution containing an alkaline compound to a hydrosol containing an alumina hydrate particle at a temperature of 10 to 100° C. and a pH of 4.5 to 6.5; washing the resultant to remove a contaminating ion; forming the washed product after dehydration so as to have a moisture content at which it is formable; drying the resultant; impregnating the dried product with a catalytic component aqueous solution containing at least one kind of periodic table group 6 metal compound, at least one kind of periodic table group 8-10 metal compound, at least one kind of phosphorus compound, and at least one kind of saccharide; and drying the resultant; a manufacturing method for the catalyst; and a hydrodesulfurization treatment method for hydrocarbon oil using the catalyst.

TECHNICAL FIELD

The present invention relates to a hydrotreating catalyst forhydrocarbon oil effective as a hydrotreating catalyst for hydrocarbonoil such as a kerosene-gas oil fraction or the like, a manufacturingmethod therefor, and a hydrotreating method for hydrocarbon oil usingthe same.

BACKGROUND ART

At present, human beings are facing serious environmental destruction ona global scale. For example, sulfur oxide (SOx), nitrogen oxide (NOx),and particulates, which are generated by combustion of fossil fuel suchas petroleum or coal, are released into the atmosphere to destruct aglobal environment remarkably. In particular, sulfur oxide causes acidrain, destructs an environment such as a forest or a lake, and makes alarge influence on ecosystem.

The motor vehicle industry is extensively developing a technology foraddressing exhaust gas, and is promoting research and development ofnovel technologies such as a combination of high-pressure injection andexhaust gas recirculation (EGR), homogeneous charge intelligent multipleinjection, and an NOx catalyst. A concentration of sulfur in gas oil isdecreased in order to alleviate influences on application of the EGReffective for a decrease in NOx and an aftertreatment apparatus forremoving particulates.

This EGR is a technology for recirculating exhaust gas to decrease aconcentration of oxygen in an engine and to make a combustiontemperature lower, to thereby decrease production of NOx, and a cool EGRusing an EGR cooler is more effective. Also in this technology, whichhas already been put into practical use in an gasoline engine, when acontent of sulfur in a fuel is large, sulfur is accumulated as sulfuricacid in an engine and abrades engine parts such as a cylinder and apiston ring, and hence it is necessary to decrease a concentration ofsulfur. Further, SO₂, which is produced by combustion of sulfur, servesas a poisoning substance for an oxidation catalyst for treating asoluble organic fraction (SOF: solvent soluble content) in particulatesor a reduction catalyst for NOx. From this viewpoint as well, there is ademand for a decrease in concentration of sulfur in gas oil as fuel.

Constituents of the particulates are a sulfate derived from a sulfurcompound in gas oil, soot (carbon; black smoke), and an SOF, andcontents of the soot and the SOF are substantially the same. Gas oilsubjected to deep desulfurization (sulfur concentration: 500 ppm) hassubstantially no sulfate content and is constituted only of the soot andthe SOF. However, SOx, which is produced by combustion of sulfur, servesas a poisoning substance for the oxidation catalyst for treating the SOFor the reduction catalyst for NOx. From this viewpoint as well, there isa demand for an additional decrease in concentration of sulfur.

From such viewpoint, there is a particularly strict regulation on acontent of sulfur in a petroleum fraction such as gasoline, kerosene-gasoil, or fuel oil, and there is a demand for development of ahydrotreating catalyst having an excellent activity of efficientlyremoving sulfur in a petroleum fraction.

A hydrodesulfurization catalyst for removing sulfur in a petroleumfraction, which is used industrially at present, is generally obtainedby supporting molybdenum or tungsten and cobalt or nickel on a porousalumina support. It is known that a desulfurization activity of suchhydrodesulfurization catalyst is remarkably affected by a supportedstate of a catalytic metal on a support. As a method involving improvingthe supported state to improve the activity of the hydrodesulfurizationcatalyst, there is known a hydrodesulfurization catalyst using a poroustitania support, having a relative desulfurization activity increased by2-fold or more as compared to a catalyst using an alumina support.

However, titania has drawbacks such as having a small specific surfacearea, having poor formability, and having low mechanical strength ascompared to alumina. In addition, titania is high in raw material priceand thus is economically disadvantageous as compared to alumina. Hence,titania is seldom used industrially as the hydrodesulfurizationcatalyst.

Various studies have been made in order to overcome those drawbacks ofthe titania support. For example, Patent Literature 1 proposes a methodinvolving increasing a specific surface area of titania and increasing adesulfurization activity. This method includes adding an anion or acation as a particle growth inhibitor to a titanium hydrous oxidehydrosol or hydrogel manufactured by a pH swing method or a driedproduct thereof, and drying and calcining the mixture, thereby giving ahigh-performance hydrodesulfurization catalyst excellent in thermalstability, having a large specific surface area, containing a highlydispersed catalytic metal, having an improved catalytic activity, andhaving high mechanical strength. However, also in this method, sucheconomic disadvantages that a titania raw material cost is high, and amass of a catalyst to be filled per volume of a reactor becomes largebecause of a large compact bulk density of the catalyst have not beenovercome yet.

In view of the foregoing, in order to provide a catalyst not onlyexcellent in economic efficiency but also excellent in performance as ahydrodesulfurization catalyst (i.e., having high activity and excellentmechanical strength), various studies have been made on realizing thecatalyst using a complex of alumina, which is low in raw material cost,and titania, which can be expected to exhibit high performance. Forexample, Patent Literature 2 discloses a technology according to amanufacturing method for a catalyst support for a hydrorefiningtreatment using a complex of an aluminum ion and a titanium ion formedby coprecipitation. Further, for example, Patent Literature 3 disclosesa manufacturing method for an alumina/titania complex catalyst supportinvolving adding a titanium hydroxycarboxylic acid salt and/or atitanium oxide or hydroxide sol and hydroxycarboxylic acid to aluminumoxide and/or hydroxide, and kneading and calcining the mixture.

However, in those technologies, improvements are found in terms ofeconomic efficiency and catalytic strength by the addition of alumina,but in terms of catalytic activity, a content of titanium oxidedecreases, and only performance depending on a mixing ratio betweentitanium oxide and alumina is exhibited.

As a method of overcoming such drawbacks, for example, Patent Literature4 discloses a method involving introducing tetrachloride titanium gasinto an alumina support to carry out chemical vapor deposition oftitanium on a surface of alumina, thereby apparently coating a poresurface of the alumina support with titania. However, this method usesgaseous titanium tetrachloride. Hence, it is necessary to repeat theoperation in order to increase an addition amount of titania, and thereis a problem in terms of industrial productivity. In addition, owing toa reaction of TiCl₄ and H₂O, HCl gas is inevitably generated, and henceit is necessary to take countermeasures for corrosion of a manufacturingfacility and environmental pollution as well into consideration.

Further, for example, Patent Literature 5 discloses a method involvingimpregnating an alumina support with a solution containing titanium tocoat a pore surface of alumina with titanium. However, this method alsohas a problem in terms of industrial productivity because it isnecessary to repeat an impregnation operation and a drying orcalcination operation in order to increase an addition amount oftitania. Further, the solution containing titanium is impregnated intopores of the alumina support, and hence physical properties such as apore volume and a specific surface area of the alumina supportinevitably deteriorate. Thus, it is difficult to improve performance ofa hydrodesulfurization catalyst to a large extent.

Meanwhile, for example, Non Patent Literature 1 discloses a methodinvolving providing a titania-alumina support by precipitation oftitanium hydroxide on a surface of an alumina hydrate particle(coating), followed by aging, filtration, washing, forming, andcalcination. However, the method according to the technology has adrawback in that an aggregate of titania is produced when an amount oftitanium is more than 9.1% by weight, resulting in decreases in specificsurface area and pore volume of alumina, although thermal stability andmechanical strength are improved.

The inventors of the present invention have already disclosed a catalystmanufacturing technology capable of manufacturing a catalyst which isexcellent in specific surface area and mechanical strength and has ahydrodesulfurization catalyst activity comparable to that of a titaniahydrodesulfurization catalyst based on such a phenomenon that aninorganic oxide and titanium oxide are chemically and microscopicallyintegrated with each other even when titanium oxide is supported in anamount of 13% by mass or more by precipitating and stacking titaniumoxide between both isoelectric points of the inorganic oxide andtitanium oxide in supporting titanium oxide on a surface of theinorganic oxide (Patent Literature 6).

In addition, various studies have been made on an improvement inactivity of a hydrotreating catalyst by using an organic compound insupporting a catalytic metal on a support.

For example, Patent Literature 7 discloses a manufacturing method for ahydrotreating catalyst involving impregnating an alumina support with acatalytic component-containing aqueous solution containing a catalyticmetal, phosphoric acid, and additives including a dihydric or trihydricalcohol having 2 to 10 carbon atoms per molecule, an ether thereof, amonosaccharide, a disaccharide, and a polysaccharide, and drying thesupport at 200° C. or less.

Further, Patent Literature 8 discloses a manufacturing method for ahydrotreating catalyst having a catalytic metal supported on a supportobtained by supporting an aqueous solution containing a titaniumcompound on an alumina hydrogel, followed by calcination. The “DetailedDeception of the Invention” section of the patent literature describesthat a water-soluble organic compound is preferably added to a catalyticcomponent-containing aqueous solution. In addition, the literaturementions, as the water-soluble organic compound, for example, a diol, analcohol, an ether group-containing water-soluble polymer, a saccharide,and a polysaccharide each having a molecular weight of 100 or more andhaving a hydroxy group and/or an ether bond.

None of those two patent literatures discloses any organic compoundparticularly effective for a catalytic activity.

CITATION LIST Patent Literature

-   [PTL 1] JP 2002-28485 A-   [PTL 2] JP 05-96161 A-   [PTL 3] JP 05-184921 A-   [PTL 4] JP 06-106061 A-   [PTL 5] JP 2001-276626 A-   [PTL 6] JP 2004-33819 A-   [PTL 7] JP 06-226108 A-   [PTL 8] JP 2002-85975 A

Non Patent Literature

-   [NPL 1] Mat. Res. Soc. Symp. Proc. Vol. 346 445-450 1994

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a manufacturing methodfor a hydrotreating catalyst for hydrocarbon oil using a titania-coatedalumina support, the hydrotreating catalyst having an additionallyimproved hydrodesulfurization activity, a hydrotreating catalyst forhydrocarbon oil manufactured by the manufacturing method, and ahydrodesulfurization treatment method for hydrocarbon oil using thesame.

Solution to Problem

The inventors of the present invention have found that the object of thepresent invention can be achieved through the use of a hydrotreatingcatalyst for hydrocarbon oil obtained by impregnating a titania-coatedalumina support having physical properties improved by uniformly coatinga surface of an alumina hydrate particle with titanium hydroxide underparticular coating conditions with a periodic table group 6 metalcompound, a periodic table group 8-10 metal compound, and a phosphoruscompound as catalytic components and a particular saccharide, and dryingthe support. That is, the present invention is as described below.

<1> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil, the method including:

a titania coating step including simultaneously and continuously addingan aqueous solution of an acidic compound containing titanium and anaqueous solution containing an alkaline compound to a hydrosolcontaining an alumina hydrate particle at a temperature ranging from 10to 100° C. and a pH ranging from 4.5 to 6.5, and coating a surface ofthe alumina hydrate particle with a titanium hydroxide particle whilekeeping the pH constant to give a titania-coated alumina hydrateparticle;

a washing step of washing the resultant titania-coated alumina hydrateparticle to remove a contaminating ion which coexists with the particle;

a forming step of forming the washed titania-coated alumina hydrateparticle after dehydrating the particle so as to have a moisture contentat which the particle is formable;

a first drying step of drying a titania-coated alumina hydrate particleformed article obtained by the forming to give a titania-coated aluminasupport;

an impregnating step of impregnating the resultant titania-coatedalumina support with a catalytic component-containing aqueous solutioncontaining at least one kind of periodic table group 6 metal compound,at least one kind of periodic table group 8-10 metal compound, and atleast one kind of phosphorus compound as catalytic components, and asaccharide (hereinafter, sometimes simply referred to as “catalyticcomponent-containing aqueous solution”); and

a second drying step of drying the titania-coated alumina supportimpregnated with the catalytic component-containing aqueous solution.

<2> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to the above-mentioned item <1>, in which the saccharideto be used in the impregnating step includes at least one kind ofsaccharide selected from the group consisting of erythritol, arabinose,xylose, xylitol, ribose, fructose, sorbose, glucose, mannose, galactose,sorbitol, mannitol, invert sugar, dulcitol, sucrose, lactose, maltose,trehalose, maltitol, isomerized sugar, and raffinose.

<3> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to the above-mentioned item <1>, in which the saccharideto be used in the impregnating step includes at least one kind ofsaccharide selected from the group consisting of erythritol, xylose,xylitol, sorbitol, mannitol, invert sugar, maltose, trehalose, maltitol,isomerized sugar, and raffinose.

<4> A manufacturing method for a hydrotreating catalyst according to anyone of the above-mentioned items <1> to <3>, in which a crystal systemof the alumina hydrate particle includes boehmite, pseudoboehmite,and/or an alumina gel.

<5> A manufacturing method for a hydrotreating catalyst according to anyone of the above-mentioned items <1> to <4>, in which a pore sharpnessdegree of the alumina hydrate particle after calcination at 500° C. for3 hours is 60% or more.

<6> A manufacturing method for a hydrotreating catalyst according to anyone of the above-mentioned items <1> to <5>, in which a temperaturecondition of the titania coating step is a temperature ranging from 15to 90° C.

<7> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to any one of the above-mentioned items <1> to <6>, inwhich an operation of the titania coating step is carried out under thefollowing conditions for (a) pH and (b) coating time:

(a) pH: within a pH variation range of ±0.5 with respect to a pH to bedetermined with the following equation (1):

pH=6.0−0.03×T  Equation (1)

in the equation (1), T represents a ratio (mass %) of titania withrespect to a whole of the titania-coated alumina hydrate particle (oxidebasis); and

(b) coating time: within a range of 5 minutes to 5 hours.

<8> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to any one of the above-mentioned items <1> to <7>, inwhich an amount of titanium hydroxide with which the alumina hydrateparticle is coated falls within a range of 5 to 40% by mass with respectto a total amount on an oxide basis.

<9> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to any one of the above-mentioned items <1> to <8>, inwhich an aging time in the impregnating step falls within a range of 10minutes to 24 hours.

<10> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to any one of the above-mentioned items <1> to <9>, inwhich the periodic table group 6 metal to be used in the impregnatingstep includes molybdenum and the periodic table group 8-10 metalincludes cobalt and/or nickel.

<11> A manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to any one of the above-mentioned items <1> to <10>, inwhich an addition amount of the saccharide to be used in theimpregnating step falls within a range of 1 to 20% by mass with respectto a total amount on an oxide basis of the support and the catalyticcomponents.

<12> A hydrotreating catalyst for hydrocarbon oil, which is manufacturedby the manufacturing method for a hydrotreating catalyst for hydrocarbonoil according to any one of the above-mentioned items <1> to <11>.

<13> A hydrotreating catalyst for hydrocarbon oil according to theabove-mentioned item <12>, in which the catalyst has supported thereon aperiodic table group 6 metal compound, a periodic table group 8-10 metalcompound, a phosphorus compound, and a saccharide.

<14> A hydrotreating catalyst for hydrocarbon oil according to theabove-mentioned item <12> or <13>, in which a repetition length of acrystal lattice plane of titania in the titania-coated alumina supportis 50 Å or less.

<15> A hydrotreating catalyst for hydrocarbon oil according to any oneof the above-mentioned items <12> to <14>, in which a pore sharpnessdegree of the titania-coated alumina support is 60% or more.

<16> A hydrotreating catalyst for hydrocarbon oil according to any oneof the above-mentioned items <12> to <15>, in which a pore volume of thetitania-coated alumina support is 0.36 to 1.10 ml/g.

<17> A hydrotreating catalyst for hydrocarbon oil according to any oneof the above-mentioned items <12> to <16>, in which a specific surfacearea of the titania-coated alumina support is 200 m²/g or more.

<18> A hydrotreating catalyst for hydrocarbon oil according to any oneof the above-mentioned items <12> to <17>, in which a compact bulkdensity (CBD) of the catalyst is 0.5 to 1.1 g/ml.

<19> A hydrodesulfurization treatment method for hydrocarbon oil,including using a hydrotreating catalyst for hydrocarbon oilmanufactured by the manufacturing method for a hydrotreating catalystfor hydrocarbon oil according to any one of the above-mentioned items<1> to <11>.

Advantageous Effects of Invention

According to the present invention, it is possible to provide themanufacturing method for a hydrotreating catalyst for hydrocarbon oilusing a titania-coated alumina support having physical propertiesimproved by uniform coating under particular coating conditions, thehydrotreating catalyst having an additionally improvedhydrodesulfurization activity as compared to a conventional catalyst,the hydrotreating catalyst for hydrocarbon oil manufactured by themanufacturing method, and the hydrodesulfurization treatment method forhydrocarbon oil using the same. They can be effectively utilized in thehydrodesulfurization treatment of hydrocarbon oil, in particular, gasoil.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A graph showing an X-ray diffraction pattern of atitania-coated alumina support AT-2 prepared under conditions of asupport production step in the present invention.

[FIG. 2] A graph showing differential pore distributions of an aluminasupport AS-2 and a titania-coated alumina support AT-2 correspondingthereto.

[FIG. 3] A graph showing an X-ray diffraction pattern of atitania/alumina-mixed support AT-14 prepared by mixing titaniumhydroxide/alumina hydrate gels.

[FIG. 4] A graph showing an X-ray diffraction pattern of atitania-coated alumina support AT-13 prepared under different conditionsfrom those of the support production step in the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention is described in detail.

A: Manufacturing Method for Hydrotreating Catalyst for Hydrocarbon Oil

A manufacturing method for a hydrotreating catalyst for hydrocarbon oilaccording to the present invention (hereinafter, sometimes simplyreferred to as “manufacturing method of the present invention”) includesa titania coating step, a washing step, a forming step, a first dryingstep, an impregnating step, and a second drying step. Hereinafter, thesteps are described in the order of the steps.

(Titania Coating Step)

In the present invention, the titania coating step is a step includingsimultaneously and continuously adding an aqueous solution of an acidiccompound containing titanium and an aqueous solution containing analkaline compound to a hydrosol containing an alumina hydrate particleat a temperature ranging from 10 to 100° C. and a pH ranging from 4.5 to6.5, and coating a surface of the alumina hydrate particle with atitanium hydroxide particle while keeping the pH constant to give atitania-coated alumina hydrate particle.

A crystal system of the alumina hydrate particle in the hydrosol as oneof the raw materials to be used in this step may be exemplified byboehmite, pseudoboehmite, and an alumina gel. Any of the crystal systemsmay be used, and a mixture of the crystal systems may also be used.

As for the alumina hydrate particle, the pore volume of the particleafter calcination at 500° C. for 3 hours is preferably 0.36 to 1.10ml/g. When the pore volume is less than 0.36 ml/g, a compact bulkdensity in supporting a catalytic metal becomes higher (e.g., more than1.1 g/ml), which makes it difficult to fill the catalyst into theexisting hydrodesulfurization facility in terms of filling weight. Onthe other hand, when the pore volume is more than 1.10 ml/g, even in thecase of supporting a catalytic metal, a catalyst particle side crushingstrength (SCS) becomes lower (e.g., less than 0.6 kg/mm on a diameter 1mmφ basis), which may make it impossible to keep a practical strength.

As for the alumina hydrate particle, the pore sharpness degree of theparticle after calcination at 500° C. for 3 hours is preferably 60% ormore, more preferably 70% or more.

Herein, the “pore sharpness degree” is a numerical value that definesthe uniformity of a pore diameter. That is, a pore sharpness degreecloser to 100% means that the pore diameter of a catalyst or a supportis uniform and consistent. That is, a pore diameter (median diameter) at50% of a pore volume is determined, a partial pore volume (PVM) presentwithin a pore diameter range of ±5% with respect to a logarithmic valueof the median diameter is then determined, and a pore sharpness degreeis determined with the following equation from the partial pore volume(PVM) and the pore volume (PVT).

Pore sharpness degree (%)=(PVM/PVT)×100

The pore sharpness degree may be calculated with the equation from acumulative pore distribution curve measured by a mercury intrusionmethod.

A preparation method for the alumina hydrate particle to be used is notparticularly limited. However, the alumina hydrate particle ispreferably synthesized by a pH swing method. When the alumina hydrateparticle is synthesized by the pH swing method, the alumina hydrateparticle having a homogeneous shape can be obtained, and alumina havinga pore sharpness degree of 60% or more can be obtained.

It should be noted that the synthesis of the alumina hydrate particle bythe pH swing method is described in detail, for example, in JP 56-120508B and JP 57-44605 B.

A contaminating ion derived from an alumina compound as a raw materialis present in a hydrosol containing the alumina hydrate particlemanufactured by the pH swing method. The contaminating ion may or maynot be removed by washing prior to the subsequent titanium hydroxidecoating operation (operation of the titania coating step in the presentinvention).

The titania coating step includes adding an aqueous solution of anacidic compound containing titanium and an aqueous solution containingan alkaline compound to the alumina hydrate particle, and uniformlycoating a surface of the alumina hydrate particle with a titaniumhydroxide particle so that the titanium hydroxide particle is supportedon the surface of the alumina hydrate particle to give a titania-coatedalumina hydrate particle.

The “acidic compound containing titanium” (hereinafter, sometimes simplyreferred to as “titanium compound”) is preferably titanium sulfate,titanyl sulfate, titanium chloride, titanium peroxide, titanium oxalate,titanium acetate, or the like.

An addition method for an aqueous solution of a titanium compound to analumina hydrate particle includes simultaneously and continuously addingan aqueous solution of a titanium compound and an aqueous solutioncontaining an alkaline compound to a hydrosol having dispersed thereinan alumina hydrate particle under particular temperature and pHconditions.

The temperature condition at this time is a temperature ranging from 10to 100° C. For example, when the alumina hydrate particle ismanufactured and the aqueous solution of a titanium compound issubsequently added, the temperature condition is a temperature rangingfrom approximately 50 to 100° C., which varies depending on thetemperature condition during the manufacture of the alumina hydrateparticle. When the alumina hydrate particle is manufactured and storedand the temperature decreases, the temperature condition is atemperature ranging from approximately room temperature to 50° C. Inthis regard, however, the temperature condition is preferably atemperature ranging from 15 to 80° C.

Meanwhile, the pH condition at this time is a pH ranging from 4.5 to6.5, and the aqueous solution of a titanium compound and the aqueoussolution containing an alkaline compound are simultaneously andcontinuously added while the pH is kept constant. It should be notedthat, when a large-capacity coating reactor is used, it is difficult tokeep the pH exactly constant. Thus, the “keeping constant” as usedherein refers to an act of controlling the pH to as close a value aspossible to a pH value of interest, preferably an act of controlling thepH within a range of ±0.5 with respect to a pH value of interest.

A principle of the pH condition is described.

When an alumina hydrate particle is coated with a titanium hydroxideparticle, the isoelectric point of the alumina hydrate particle coatedwith titanium hydroxide varies depending on the coating amount. Table 1below shows isoelectric point measurement results depending on differentcoating amounts of titanium hydroxide.

TABLE 1 Coating amount of titanium Isoelectric point (pH) hydroxideparticle (mass %) measurement results 0 10.0 10 9.2 20 8.5 30 7.8 40 7.250 6.6 100 4.2

In Table 1 above, the coating amounts of titanium hydroxide are eachexpressed in terms of mass ratio (%) with respect to a total on an oxidebasis of titanium hydroxide and the alumina hydrate particle, and 100%of the titanium hydroxide particle and 100% of the alumina hydrateparticle represent a case of only the titanium hydroxide particle and acase of only the alumina hydrate particle, respectively. In thefollowing description, the “coating amount of titanium hydroxide”similarly means amass ratio (%) with respect to a total on an oxidebasis of titanium hydroxide and the alumina hydrate particle.

It should be noted that the isoelectric point was measured by anelectrophoretic light scattering method using an HLS-8000 type apparatusmanufactured by Otsuka Electronics Co., Ltd. as a measurement apparatus.The isoelectric point was determined as follows: a pH at which a zetapotential was 0 was determined based on a relationship between themeasured pH and zeta potential; and the pH was adopted as theisoelectric point.

In theory, the pH in the case of coating the surface of the aluminahydrate particle with the titanium hydroxide particle has only to fallwithin a range of values more than pH=4.2, which is an isoelectric pointin 100% of the titanium hydroxide particle, and less than an isoelectricpoint corresponding to a concentration of each titanium hydroxideparticle (coating amount of titanium hydroxide). For example, when theconcentration of the titanium hydroxide particle is 10%, the pH is lessthan pH=9.2 (see Table 1).

However, the pH in the case of uniformly and strongly coating thesurface of the alumina hydrate particle with titanium hydroxidepreferably falls within a range of 4.5 to 6.5 as defined in theinvention of the present application. The reason for this is as follows:the zeta potential of the titanium hydroxide particle is controlled to−5.0 mV or less (5.0 mV or more in terms of absolute value) bycontrolling the pH to 4.5 or more; the zeta potential of thetitania-coated alumina hydrate particle is controlled to 20 mV or more(20 mV or more in terms of absolute value) by controlling the pH to 6.5or less; and consequently, titanium hydroxide and the titania-coatedalumina hydrate particle are constantly charged negatively andpositively, respectively, and thus can be strongly bonded to each other.That is, the surface of the alumina hydrate particle is efficiently andstrongly coated with titanium hydroxide through an attractiveinteraction based on a positive/negative relationship by controlling thepH within the range as defined in the invention of the presentapplication.

The operation of the titania coating step is more preferably carried outunder the following conditions for (a) pH and coating time:

(a) pH: within a pH variation range of ±0.5 with respect to a pH to bedetermined with the following equation (1):

pH=6.0−0.03×T  Equation (1)

in the equation (1), T represents the coating amount of titaniumhydroxide; and

(b) coating time: within a range of 5 minutes to 5 hours.

When the operation of the titania coating step is carried out under theabove-mentioned pH condition, a total of absolute values of the zetapotentials of the titanium hydroxide particle and the titania-coatedalumina hydrate particle is effectively kept in the vicinity of themaximum value, and the surface of the alumina hydrate particle is morestrongly coated with titanium hydroxide.

The equation (1) is a relational equation obtained by actually measuringrelationships between the zeta potentials of the titanium hydroxideparticle and the titania-coated alumina hydrate particle and the pH, andderiving a condition under which both the zeta potentials areeffectively split in positive and negative ones through the use of thecoating amount of titanium hydroxide as a variable.

Meanwhile, when the coating time of titanium hydroxide is less than 5minutes, it is difficult to keep the pH exactly constant at apredetermined value in the case of using a large-capacity coatingreactor, resulting in difficulty in uniformly and strongly coating thealumina hydroxide particle with titanium hydroxide. When the coatingtime is more than 5 hours, the manufacturing efficiency oftitania-coated alumina hydrate decreases to a large extent. Accordingly,both the cases are not preferred.

Titanium hydroxide with which the surface of the alumina hydrateparticle is coated under the conditions defined in the present inventionis characterized by showing no crystal structure of anatase as titaniumhydrate in analysis results by X-ray diffraction. The analysis resultsare described, in the first drying step, as the analysis results of atitania-coated alumina support obtained through the step.

In the present invention, the coating amount of the titanium hydroxideparticle with which the surface of the alumina hydrate particle iscoated falls within preferably a range of 5 to 40% by mass, morepreferably a range of 10 to 35% by mass. When the coating amount is lessthan 5% by mass, an effect by addition of titanium hydroxide may not besufficiently exhibited. When the coating amount is more than 40% bymass, particles of titanium hydroxide aggregate to each other, and hencethe surface of the alumina hydroxide particle may not be uniformlycoated with titanium hydroxide. Accordingly, both the cases are notpreferred.

(Washing Step)

The reaction liquid after the titania-coated alumina hydrate particlehas been obtained by coating the surface of the alumina hydrate particlewith the titanium hydroxide particle generally contains contaminatingions such as a sodium ion or an ammonia ion as a cation and a sulfuricacid ion or a chlorine ion as an anion. Thus, the resultanttitania-coated alumina hydrate particle is washed in this washing step.The washing allows the contaminating ions to be removed or reduced. Thewashing is carried out by a washing/filtration operation involvingrinsing with water through the use of an Oliver filter, a press filter,or the like.

(Forming Step)

The titania-coated alumina hydrate particle obtained by the operation ofthe washing step is dehydrated so as to have a moisture content at whichthe particle is formable. The dehydration is generally carried out by anoperation such as press filtration, vacuum filtration, or centrifugationfiltration, and may be carried out by drying. In addition, thedehydration may be carried out by a combination of those operations.

After the dehydration, the particle is formed into a shape suitable fora use purpose, such as a columnar shape, a clover shape, a cylindricalshape, or a spherical shape to give a titania-coated alumina hydrateparticle formed article.

(First Drying Step)

The first drying step is a step of stabilizing the titania-coatedalumina hydrate particle formed article obtained in the forming stepthrough an operation of drying or drying and the subsequent calcination.A temperature at which the drying or drying and the subsequentcalcination is carried out falls within preferably a range of 100 to600° C., more preferably a range of 120 to 500° C. When the treatment iscarried out at a temperature of less than 100° C., the drying requiresmuch time, which is not practical. Further, when the temperature is morethan 600° C., a crystal form of anatase is observed and the coating withtitanium hydroxide becomes non-uniform.

It should be noted that the operation of only the drying and theoperation of the drying and the subsequent calcination are substantiallythe same except that the heating temperatures are different from eachother, and hence the “drying” comprehends the concept of “calcination”in the present invention (the same holds true for the second dryingstep).

In this step, it is preferred that the drying time be appropriatelyselected from a range of 0.5 to 24 hours.

A titania-coated alumina support is obtained through the operation ofthis step.

In the operations of the steps described above, as a feature in the caseof obtaining the titania-coated alumina support by coating with titaniumhydroxide, there is a tendency that the specific surface area of atitanium hydroxide-supporting alumina particle becomes larger than thespecific surface area of the alumina hydrate particle serving as a base.In addition, such a feature that the specific surface area does notdecrease even when the total pore volume increases is also found. In thepresent invention, a hydrodesulfurization catalyst having a very highactivity can be prepared while keeping the compact bulk density of thecatalyst at an appropriate value (e.g., 1.1 g/ml or less) by making themost of those features.

As described above, titanium hydroxide with which the surface of aluminahydrate is coated under the conditions of the titania coating step inthe present invention is characterized by showing no crystal structureof anatase as titanium hydrate in analysis results by X-ray diffraction.

A case where a main peak 2θ=26.5° of anatase is detected with a generalX-ray diffraction apparatus suggests the presence of an aggregate oftitanium hydrate, and it cannot be said that the coating has beencarried out optimally. However, a case where this peak is not detectedindicates that the surface of the alumina hydrate particle has beenstrongly and uniformly coated with titanium hydroxide, and suggests thatthe repetition length of the crystal lattice plane of titanium hydroxideis 50 Å or less.

FIG. 1 shows an example of an XRD measurement result (X-ray diffractionpattern) of titania-coated alumina produced under the conditions of thetitania coating step in the present invention. This is specifically ameasurement result of a titania-coated alumina AT-2 used in Examples tobe described later.

Meanwhile, it is highly probable that titanium hydroxide in the case ofcoating under different conditions from those defined in the presentinvention shows a crystal structure of anatase as titanium hydrate inanalysis results by X-ray diffraction, and it is also highly probablethat no strong coating is not carried out. For example, in the case ofcoating with 30% by mass on an oxide basis of titanium hydroxide whilekeeping the pH at 8.0, charges of titanium hydroxide and thetitania-coated alumina hydrate particle are both negative and hencerepel each other, with the result that no strong coating is carried out.

FIG. 4 shows an XRD pattern in this state. This is specifically ameasurement result of a titania-coated alumina support AT-13 to bedescribed later.

(Impregnating Step)

The impregnating step is a step of impregnating the titania-coatedalumina support obtained in the first drying step with an aqueoussolution containing catalytic components including at least one kind ofperiodic table group 6 metal compound and at least one kind of periodictable group 8-10 metal compound as catalytic metal compounds and atleast one kind of phosphorus compound, and at least one kind ofsaccharide.

After the impregnation with the catalytic component-containing aqueoussolution, aging is carried out as necessary in order to uniformlystabilize an active metal on the titania-coated alumina support. Itshould be noted that the “aging” refers to that the support isimpregnated with the catalytic component-containing aqueous solution andthen left to stand still in that state. In the present invention, thisaging operation is also included in one of the operations of the“impregnating step.” The aging time falls within preferably a range of10 minutes to 24 hours.

Examples of the periodic table group 6 metal include molybdenum andtungsten. In particular, molybdenum is preferred. A preferred molybdenumcompound is exemplified by molybdenum trioxide and ammonium p-molybdate.The loading of each of those periodic table group 6 metal compoundsfalls within preferably a range of 10 to 40% by mass, more preferably arange of 15 to 35% by mass with respect to the catalyst (total amount onan oxide basis of the support+the periodic table group 6 and 8-10 metalcompounds+the phosphorus compound, the same applies hereinafter).

Examples of the periodic table group 8-10 metal include cobalt andnickel. A preferred nickel compound is exemplified by nickel nitrate andbasic nickel carbonate, and a preferred cobalt compound is exemplifiedbycobalt nitrate and basic cobalt carbonate. Those cobalt compounds andnickel compounds may be used alone or in combination. The loading(addition amount) of each of those active metal compounds falls withinpreferably a range of 1 to 10% by mass, more preferably a range of 2 to8% by mass with respect to the catalyst.

Examples of the phosphorus compound include phosphorus pentoxide andorthophosphoric acid. The loading (addition amount) of the phosphoruscompound falls within a range of 1 to 10% by mass, preferably a range of2 to 8% by mass with respect to the catalyst.

Examples of the saccharide include: monosaccharides such as trioses(glyceraldehyde, dihydroxyacetone, and glycerine), tetroses (such aserythrose, threose, erythrulose, and erythritol), pentoses (such asribulose, xylulose, ribose, arabinose, xylose, xylitol, lyxose, anddeoxyribose), hexoses (such as psicose, fructose, sorbose, tagatose,allose, altrose, glucose, mannose, gulose, idose, galactose, talose,fucose, fuculose, rhamnose, sorbitol, mannitol, dulcitol, galactitol,glucosamine, galactosamine, inositol, and invert sugar), and heptoses(such as sedoheptulose); disaccharides such as sucrose, lactose,maltose, trehalose, maltitol, turanose, cellobiose, gentiobiose,isomaltose, kojibiose, laminaribiose, melibiose, nigerose, andsophorose; trisaccharides such as raffinose, melezitose, andmaltotriose; tetrasaccharides such as acarbose and stachyose;oligosaccharides such as fructo-oligosaccharide,galacto-oligosaccharide, and mannan-oligosaccharide; polysaccharidessuch as glycogen, starch, cellulose, dextrin, glucan, fructan, guar gum,and N-acetyl glucosamine; and isomerized sugar.

The saccharide in the present invention is preferably erythritol,arabinose, xylose, xylitol, ribose, fructose, sorbose, glucose, mannose,galactose, sorbitol, mannitol, invert sugar, dulcitol, sucrose, lactose,maltose, trehalose, maltitol, isomerized sugar, or raffinose. Those maybe used alone or as a mixture of two or more kinds thereof.

Moreover, the saccharide in the present invention is particularlypreferably erythritol, xylose, xylitol, a hexose such as sorbitol,mannitol, or invert sugar, maltose, trehalose, maltitol, isomerizedsugar, or raffinose.

The addition amount of the saccharide falls within preferably a range of1 to 20% by mass, more preferably a range of 5 to 15% by mass in termsof outer percentage with respect to the catalyst.

(Second Drying Step)

Next, the titania-coated alumina support impregnated with the catalyticcomponent-containing aqueous solution in the impregnating step is driedin order to stabilize the catalytic components and the saccharide on thetitania-coated alumina support. The drying temperature falls withinpreferably a range of 100 to 500° C. It is also possible to carry outheating continuously after the drying, i.e., calcination. The dryingtime falls within a range of 0.5 to 24 hours.

A hydrotreating catalyst for hydrocarbon oil exhibiting a high catalyticactivity can be manufactured through the operations of the stepsdescribed above.

B: Hydrotreating Catalyst for Hydrocarbon Oil

The hydrotreating catalyst for hydrocarbon oil of the present invention(hereinafter, sometimes referred to as “hydrotreating catalyst of thepresent invention” or simply referred to as “catalyst of the presentinvention”) is manufactured by the manufacturing method of the presentinvention as described above. With this, the catalyst of the presentinvention has supported thereon the periodic table group 6 metalcompound, the periodic table group 8-10 metal compound, the phosphoruscompound, and the saccharide.

The catalyst of the present invention, which is manufactured by themanufacturing method of the present invention, has a high pore sharpnessdegree, a large pore volume, and a large specific surface area, andprovides an appropriate compact bulk density of the catalyst.Specifically, a hydrotreating catalyst having preferred physicalproperties shown below can be obtained.

The pore sharpness degree of the titania-coated alumina supportcontained in the catalyst of the present invention is preferably 60% ormore, more preferably 70% or more. A pore sharpness degree of 60% ormore is preferred because the activity of the catalyst increases owingto the presence of a large number of pores, which are optimum for areaction, depending on the size of a reaction substance.

The pore volume of the titania-coated alumina support contained in thecatalyst of the present invention is preferably 0.36 to 1.10 ml/g. Apore volume of 0.35 ml/g or more is preferred because it is easy tocarry out the impregnation with the catalytic component-containingaqueous solution and it is also easy to control the compact bulk density(CBD) of the catalyst to 1.1 g/ml or less. On the other hand, a porevolume of more than 1.10 ml/g causes a decrease in catalyst particleside crushing strength (SCS), which may make it impossible to keep apractical strength.

The specific surface area of the titania-coated alumina supportcontained in the catalyst of the present invention is preferably 200m²/g or more. A specific surface area of 200 m²/g or more can realize ahydrorefining catalyst exhibiting a high activity.

In this description, the specific surface area was measured by a BETthree-point method. Macsorb Model-1201 manufactured by Mountech Co.,Ltd. was used as a measurement instrument.

The compact bulk density (CBD) of the catalyst of the present inventionfalls within preferably a range 0.5 to 1.1 g/ml, more preferably a rangeof 0.5 to 1.0 g/ml. When the compact bulk density (CBD) is less than 0.5g/ml, the catalyst particle side crushing strength (SCS) of the catalystbecomes lower (e.g., 0.6 kg/mm or less), with the result that thestrength may fall short of a practical strength for the catalyst.Further, when the compact bulk density (CBD) is more than 1.1 g/ml, thefilling into the existing desulfurization facility becomes difficult.Accordingly, both the cases are not preferred.

In the present invention, the compact bulk density (CBD) was measured asdescribed below. First, a catalyst fractionated between 30 to 80 (mesh)through the use of a sieve is dried at 120° C. for 3 hours, thencollected in an amount of about 30 (g), weighed precisely with ananalytical balance, and filled into a measuring cylinder made of glassand having an inner diameter of 21 mm and a volume of 50 ml. Then, themeasuring cylinder is tapped through the use of a vibrator to measure avolume at the minimum bulk. The compact bulk density (CBD) is determinedby dividing amass determined by precisely weighing the catalyst by thevolume value at the minimum bulk.

C: Hydrodesulfurization Treatment Method for Hydrocarbon Oil

The hydrotreating method for hydrocarbon oil according to the presentinvention (hereinafter, sometimes simply referred to as “hydrotreatingmethod of the present invention”) includes using the catalyst of thepresent invention manufactured by the manufacturing method of thepresent invention described above.

When the hydrodesulfurization treatment is carried out through the useof the catalyst of the present invention, it is desired to carry outpreliminary sulfurization for activating a catalytic metal. Thepreliminary sulfurization is carried out through the use of hydrogensulfide, carbon disulfide, thiophene, dimethyl disulfide, hydrocarbonoil containing any of those compounds, or the like as a preliminarysulfurization agent.

After the preliminary desulfurization, a hydrodesulfurization treatmentis carried out. A hydrodesulfurization condition varies depending on thekind of raw material oil and a purpose. In general, however, it ispreferred that a reaction temperature fall within a range of 300 to 400°C. and a hydrogen partial pressure fall within a range of 1 to 10 MPa.

A reaction mode in the hydrodesulfurization treatment is notparticularly limited and is exemplified by a fixed bed, a moving bed, anebullating bed, and a suspension bed, any of which may be adopted. Areaction condition in the case where the fixed bed is adopted ispreferably as follows: liquid hourly space velocity (LHSV) ranging from0.5 to 5 hr⁻¹; and hydrogen/raw material oil volume ratio ranging from50 to 500 Nm³/kl.

Specific examples of the hydrocarbon oil which may be treated in thepresent invention include gasoline, kerosene, light gas oil, heavy gasoil, light cycle oil, atmospheric residue, vacuum residue, oil sand oil,and tar sand oil. The catalyst of the present invention is particularlyeffective for a hydrodesulfurization treatment involving reducing thesulfur content of a gas oil fraction to 10 ppm or less.

EXAMPLES

Hereinafter, the present invention is more specifically described by wayof examples.

(Measurement Method)

Various physical properties, catalytic performance, and the like weremeasured according to the following procedures and conditions inaddition to those as described above.

(Measurement of Pore Distribution and Pore Volume)

The pore distribution and pore volume of a catalyst or a support wereeach measured by a mercury intrusion method involving applying ameasurement pressure of up to 414 MPa through the use of Autopore IV9520 Type manufactured by Shimadzu Corporation.

(X-Ray Diffraction)

The X-ray diffraction of a support was measured through the use of anX-ray diffraction apparatus (apparatus name: XPERT SYSTEM/APD-1700manufactured by PHilips) after each sample had been powderized. Itshould be noted that measurement conditions for the X-ray diffractionapparatus at this time were as described below.

X-ray source: Cu Kα

X-ray tube voltage (kV): 40

X-ray tube current (mA): 30

Measurement angle (°): 5 to 80

Slit width (mm): 0.2

Rec. Slit Fixed (mm): 0.2

(Gas Oil Hydrodesulfurization Test)

A gas oil hydrodesulfurization test for measuring the desulfurizationactivity of a hydrotreating catalyst was carried out as described below.

A high-pressure fixed-bed flow reactor was used, 15 ml of a catalystwere filled, and the test was carried out under the conditions of:reaction pressure: 5 MPa; reaction temperature: 340° C.; liquid hourlyspace velocity: 1.5 h⁻¹; and hydrogen/raw material volume ratio: 250Nl/l. The hydrotreating catalyst was subjected to the test on gas oilwhich had a sulfur concentration adjusted to 2.5% (by mass) through theaddition of dimethyl disulfide and which had been subjected to asulfurization treatment in advance (preliminary sulfurization) in allcases. The properties of Middle Eastern straight-run gas oil subjectedto the hydrodesulfurization test are as follows: specific gravity (15/4°C.): 0.850; sulfur content: 1.37% by mass; and nitrogen content: 101ppm, and the distillation properties of the oil are as follows: initialboiling temperature: 232° C.; 50% distillation temperature: 295° C.; and90% distillation temperature: 348° C.

The desulfurization activity of the hydrotreating catalyst was expressedas a “relative desulfurization activity” in the case of defining anaverage value of desulfurization reaction rate constants for ahydrotreating catalyst ASC-2 to be described later as 100 by determiningdesulfurization reaction rate constants on the assumption that adesulfurization reaction was a 1.2-order reaction, and calculating anaverage value of the desulfurization reaction rate constants for areaction time of 100 to 144 hours.

(Example of Support Manufacture)

<Preparation of Raw Material Liquid>

An A liquid obtained by adding water at a ratio of 1,030 g with respectto 970 g of aluminum chloride hexahydrate, a B liquid obtained by addingwater at ratio of 1,000 g with respect to 1,000 g of 28% aqueousammonia, a C liquid obtained by adding water to 198 g of a titaniumtetrachloride solution having a Ti concentration of 16.6% by mass and aCl concentration of 32.3% by mass so that the total volume is 1.8litters, and a D liquid obtained by adding water to 231 g of 14% aqueousammonia so that the total volume is 1.8 litters, and an E liquidobtained by adding 733 g of hydrochloric acid and 13 g of water to 1,520g of a titanium tetrachloride solution having a Ti concentration of16.7% by mass and a Cl concentration of 32.6% by mass were each preparedin a total amount necessary for the operations to be described below.

<Manufacture of Alumina Supports AS-1 to AS-5>

(Preparation of Alumina Hydrate Particle)

(a) 14 litters of water were charged into a 19-litter porcelain enamelcontainer and heated to 80° C. with stirring. 850 g of the A liquid wereadded to the porcelain enamel container and the mixture was kept for 5minutes. The pH of the liquid (hereinafter, referred to as “synthesissolution”) at this time was 2.5. Next, to the porcelain enamel containerwas added the B liquid in such an amount that the pH of the synthesissolution became 7.5 and the mixture was kept for 5 minutes (first pHswing).

(b) After that, 850 g of the A liquid were added to adjust the pH of thesynthesis solution to 3.0 and the mixture was kept for 5 minutes. The Bliquid was added thereto again in such an amount that the pH of thesynthesis solution became 7.5 and the mixture was kept for 5 minutes(second pH swing).

(c) Then, a chlorine ion and an ammonium ion as contaminants wereremoved by washing to give an alumina hydrate particle AG-1 in which thepH swing number was two times.

Further, the operation (second pH swing) and the preceding operation(operations (a) and (b)) were carried out in the same manner asdescribed above except that the addition amount of the A liquid per unitpH swing was changed to 567 g. After that, the operation (b) wasrepeated once again under such a condition that the addition amount ofthe A liquid was 567 g to give an alumina hydrate particle AG-2 in whichthe pH swing number was three times.

In addition, alumina hydrate particles AG-3, AG-4, and AG-5 in which thepH swing numbers are four times, five times, and six times were obtainedby setting the addition amounts of the A liquid per unit pH swing to 425g, 340 g, and 283 g, respectively.

The resultant alumina hydrate particles AG-1, AG-2, AG-3, AG-4, and AG-5were each filtered to adjust the moisture content to one at which theparticle was formable, molded into a columnar shape having a diameter of1.2 mm by extrusion molding, then dried at 120° C. for 16 hours, andfurther calcined at 500° C. for 3 hours. Thus, alumina supports AS-1 toAS-5 were obtained. Each of the resultant alumina supports was measuredfor its specific surface area and pore distribution. Table 2 below showsthe results collectively.

TABLE 2 Alumina support No. AS-1 AS-2 AS-3 AS-4 AS-5 pH swing number 2 34 5 6 (times) Specific surface 305 346 327 326 315 area (m²/g) Porevolume 0.43 0.5 0.59 0.65 0.81 (ml/g) Pore sharpness 70.3 65.9 79.1 75.676.2 degree (%)

<Manufacture of Titania-Coated Alumina Supports AT-1 to AT-5>

(Titania Coating Step)

122 g on an oxide basis of the alumina hydrate particle AG-1 werecollected and stirred well with a mixer while water was added to give 8litters of a dispersion liquid. To the dispersion liquid kept at 60° C.was added the C liquid to adjust the pH to 5.0. Subsequently, 1.8litters each of the C liquid and the D liquid were simultaneously andcontinuously added over about 2 hours so as to keep the pH within arange of 5.0±0.1 to manufacture a titania-coated alumina hydrateparticle. The coating amount of titania in the resultant titania-coatedalumina hydrate particle is 31%.

It should be noted that, when the coating amount of titania issubstituted into the above-mentioned equation (1),

pH=6.0−0.03×31=5.07

is established, and hence an optimum pH condition to be determined fromthe equation (1) is 5.07±0.5, which is satisfied by the pH condition ofthe titania coating step according to this example, i.e., 5.0±0.1.

(Washing Step to First Drying Step)

The resultant titania-coated alumina hydrate particle was washed withwater to remove an ammonia ion and an chlorine ion each coexisting withthe particle, filtered to adjust the moisture content to one at whichthe particle was formable, molded into a columnar shape having adiameter of 1.2 mm by extrusion molding (forming step), then dried at120° C. for 16 hours, and further calcined at 500° C. for 3 hours (firstdrying step) to give a titania-coated alumina support AT-1.

Titania-coated alumina supports AT-2, AT-3, AT-4, and AT-5 were obtainedby carrying out the coating with titanium hydroxide, forming, drying,and further calcination by the same method as in the case of thetitania-coated alumina support AG-1 except that the alumina hydrateparticle AG-1 used was changed to the alumina hydrate particles AG-2,AG-3, AG-4, and AG-5, respectively. Each of the resultant titania-coatedalumina supports was measured for its specific surface area and poredistribution. Table 3 below shows the results collectively.

TABLE 3 Titania-coated alumina support No. AT-1 AT-2 AT-3 AT-4 AT-5Specific surface area 339 400 365 357 351 (m²/g) Pore volume (ml/g) 0.470.57 0.65 0.7 0.85 Pore sharpness degree 72.9 76.5 80.1 72.1 73 (%)

As shown in Table 3, each of the titania-coated alumina supports AT-1 toAT-5 has a pore volume of 0.47 to 0.85 ml/g, which is comparable to orlarger than that of the alumina support. In addition, the results revealthat the specific surface area of each of the titania-coated aluminasupports AT-1 to AT-5 is approximately 340 to 400 m²/g, which is largerby approximately 50 m²/g than that of the alumina support containing100% of alumina. In addition, both the specific surface area and thepore volume are improved to a large extent as compared to the titaniasupport TS-1 containing 100% of titania shown in Table 4.

Each of the titania-coated alumina supports AT-1 to AT-5 preparedthrough the operations of the first drying step and the preceding stepsin the manufacturing method of the present invention was subjected toX-ray diffraction by the above-mentioned method. As a result, althoughthe content of titania was 31% by mass on an oxide basis, no anatasecrystal of titania was detected in the X-ray diffraction pattern. FIG. 1shows an X-ray diffraction pattern of the titania-coated alumina supportAT-2 as a typical example.

Further, FIG. 2 shows differential pore volume distribution plots of thealumina support AS-2 and the titania-coated alumina support AT-2. FIG. 2reveals that the pore distributions are substantially the sameirrespective of the presence or absence of coating with 31% by mass oftitania. This indicates that the alumina particle has been uniformlycoated with titanium. This is also a feature of the present invention.

<Manufacture of Titania Support TS-1 for Reference>

22 litters of water were charged into a 35-litter porcelain enamelcontainer and heated to 60° C. with stirring. 567 g of the E liquid wereadded to the porcelain enamel container and the mixture was kept for 5minutes. Next, 710 g of 14% aqueous ammonia were added to the porcelainenamel container and the mixture was kept for 5 minutes (first pHswing). After that, the E liquid and aqueous ammonia were added throughthe same operation as in the first pH swing and the mixture was kept for5 minutes (second pH swing). Subsequently, a chlorine ion and anammonium ion each coexisting with the titanium hydrate particle wereremoved by washing to give a titania hydrate particle TG-1, which wassubjected to the same operations of the forming step and the firstdrying step as in the titania-coated alumina support AT-2 to give atitania support TS-1. The resultant titania support TS-1 was measuredfor its specific surface area and pore volume. Table 4 below shows theresults.

TABLE 4 Titania support No. TS-1 Specific surface area (m²/g) 162 Porevolume (ml/g) 0.25 Pore sharpness degree (%) 86.4

<Manufacture of Titania/Alumina-Mixed Support AT-14 for Reference>

The titania hydrate particle TG-1 and the alumina hydrate particle AG-2were mixed with each other and subjected to moisture content adjustmentand the same forming step and first drying step as in AT-2 to give atitania/alumina-mixed support AT-14 containing 31% by mass of titaniaand 69% by mass of alumina. The resultant titania/alumina-mixed supportAT-14 was measured for its physical properties (specific surface areaand pore distribution) and subjected to X-ray diffraction. Table 5 belowand FIG. 3 show the measurement results of the physical properties andan X-ray diffraction pattern, respectively.

TABLE 5 Titania support No. AT-14 Specific surface area (m²/g) 320 Porevolume (ml/g) 0.49 Pore sharpness degree (%) 79.8

<Manufacture of Titania-Coated Alumina Supports AT-6 to AT-9>

Titania-coated alumina supports AT-6 to AT-9 were each manufacturedunder the same conditions as in the manufacturing step of thetitania-coated alumina support AT-2 except that, in the manufacturingstep of the titania-coated alumina support AT-2, the pH of the titaniacoating step including simultaneously and continuously adding the Cliquid and the B liquid to the dispersion liquid of the alumina hydrateparticle was changed from “5.0±0.1” to values shown in Table 6 below.Each of the resultant titania-coated alumina supports AT-6 to AT-9 wasmeasured for its specific surface area and pore distribution. Table 6below shows the results.

TABLE 6 Titania-coated alumina support No. AT-6 AT-7 AT-8 AT-9 pH oftitania 4.0 ± 0.1 6.0 ± 0.1 7.0 ± 0.1 8.0 ± 0.1 coating step Specific410 401 378 337 surface area (m²/g) Pore volume 0.5 0.56 0.6 0.46 (ml/g)Pore sharpness 68.8 75.6 69.2 71.5 degree (%) Remark For For present ForFor comparison invention comparison comparison

<Manufacture of Titania-Coated Alumina Supports AT-10 to AT-13>

Titania-coated alumina supports AT-10 to AT-13 were each manufacturedunder the same conditions as in the manufacturing step of thetitania-coated alumina support AT-2 except that, in the manufacturingstep of the titania-coated alumina support AT-2, the addition amounts ofthe B liquid and the C liquid were adjusted so that the coating amountsof titanium hydroxide were values shown in Table 7 below, and theliquids were simultaneously and continuously added. Each of theresultant titania-coated alumina supports AT-10 to AT-13 was measuredfor its specific surface area and pore distribution. Table 7 below showsthe results. Further, FIG. 4 shows an X-ray diffraction pattern of thetitania-coated alumina support AT-13 manufactured under differentconditions from those of the manufacturing method of the presentinvention.

TABLE 7 Titania-coated alumina support No. AT-10 AT-11 AT-12 AT-13Coating amount 4% 10% 20% 45% of titania* Specific 358 380 404 349surface area (m²/g) Pore volume 0.52 0.56 0.57 0.48 (ml/g) Poresharpness 69.4 76.2 80.7 69.9 degree (%) *Mass ratio of titania withrespect to a total on an oxide basis of titania and an alumina support

<Example of Hydrotreating Catalyst Manufacture>

(Preparation of Catalytic Component-Containing Aqueous Solution)

90.2 g of molybdenum oxide, 20.2 g of cobalt carbonate in terms of CoO,and 13.1 g of 85% phosphoric acid were added to water and dissolved byheating with stirring to give a catalytic component-containing aqueoussolution MS-1 in a total amount of 500 g.

A catalytic component-containing aqueous solution MS-2 was obtained byfurther dissolving 3.6 g of sorbitol in 88.0 g of the catalyticcomponent-containing aqueous solution MS-1.

Catalytic component-containing aqueous solutions MS-3 to MS-22 were eachobtained in the same manner as in the catalytic component-containingaqueous solution MS-2 except that, in the preparation of the catalyticcomponent-containing aqueous solution MS-2, respective saccharides shownTable 8 below were used in respective addition amounts shown in thetable in place of 3.6 g of sorbitol.

TABLE 8 Catalytic component aqueous Kind of Addition solution No.saccharide amount MS-1 No addition 0 of saccharide MS-2 Sorbitol 3.6MS-3 Arabinose 3.6 MS-4 Xylose 3.6 MS-5 Xylitol 3.6 MS-6 Ribose 3.6 MS-7Fructose 5.8 MS-8 Sorbose 3.6 MS-9 Glucose 5.8 MS-10 Mannose 3.6 MS-11Galactose 3.6 MS-12 Mannitol 3.6 MS-13 Dulcitol 3.6 MS-14 Sucrose 11.4MS-15 Lactose 11.4 MS-16 Maltose 7.1 MS-17 Trehalose 7.1 MS-18 Maltitol7.1 MS-19 Isomerized 7.1 sugar MS-20 Raffinose 7.1 MS-21 Erythritol 3.6MS-22 Invert 5.8 sugar

Comparative Examples 1 to 6 Manufacture of Hydrotreating Catalyst

50 g of the alumina support AS-2 obtained through the operations in thefirst drying step and the preceding steps were impregnated with 74.3 gof the catalytic component-containing aqueous solution MS-1 and furtherdried at 120° C. for 16 hours to give a hydrotreating catalyst ASC-2.

Hydrotreating catalysts ATC-2 and ATC-6 to ATC-9 were obtained in thesame manner as in the manufacture of the hydrotreating catalyst ASC-2except that, in the manufacture of the hydrotreating catalyst ASC-2, thetitania-coated alumina supports AT-2 and AT-6 to AT-9 obtained throughthe operations of the first drying step and the preceding steps wereused in place of the alumina support AS-2, respectively.

(Measurement of Physical Properties and Catalytic Physical Properties)

Each of the resultant hydrotreating catalysts ASC-2 and ATC-2 and ATC-6to ATC-9 was measured for its specific surface area, pore volume, poresharpness degree, and relative desulfurization activity (gas oilhydrodesulfurization test) by the above-mentioned method. Table 9 belowshows the results.

TABLE 9 Comparative Comparative Comparative Comparative ComparativeComparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Hydrotreating ASC-2 ATC-6 ATC-2 ATC-7 ATC-8 ATC-9 catalyst No. Specific195 234 230 231 217 192 surface area (m²/g) Pore volume 0.35 0.34 0.360.38 0.4 0.3 (ml/g) Pore sharpness 62.4 58.5 68.4 64.9 59 61 degree (%)Relative 100 145 189 183 159 130 desulfurization activity Remark AluminaPH = 4 PH = 5 PH = 6 PH = 7 PH = 8

When compounds of molybdenum, cobalt, phosphorus, and the like aresupported by an impregnation method in order to use the titania-coatedalumina support as a hydrotreating catalyst for hydrocarbon oil, thosecompounds each exhibiting an desulfurization activity are supported on atitania surface exhibiting a higher hydrodesulfurization activity thanan alumina surface. Thus, a hydrodesulfurization catalyst using thetitania-coated alumina support can exhibit higher desulfurizationactivity than a catalyst using the alumina support.

In this regard, however, in the manufacturing step of the support, whenthe pH of an alumina slurry does not fall within the range of 4.5 to 6.5during the addition of an acidic compound containing titania and analkaline compound to the alumina slurry, the non-uniformity of thecoating of alumina with titania increases, and hence a partially exposedportion is estimated to be generated in alumina. Thus, in thehydrotreating catalysts ATC-6 (Comparative Example 2), ATC-8(Comparative Example 5), and ATC-9 (Comparative Example 6) using thetitania-coated alumina supports which do not fall within the pH range,the coating of alumina with titania in the supports is estimated to bepoor, and as shown in Table 9, a decrease in desulfurization activity isobserved.

Examples 1 to 5 Manufacture of Hydrotreating Catalyst

50 g each of the titania-coated alumina supports AT-10 to AT-13 and AT-2obtained through the operations of the first drying step and thepreceding steps were impregnated with 74.3 g of the catalyticcomponent-containing aqueous solution MS-2 and further dried at 120° C.for 16 hours to give hydrotreating catalysts ATC-10 to ATC-13 andATC-14, respectively.

(Measurement of Physical Properties and Catalytic Physical Properties)

Each of the resultant hydrotreating catalysts ATC-10 to ATC-13 andATC-14 was measured for its specific surface area, pore volume, poresharpness degree, compact bulk density, and relative desulfurizationactivity (gas oil hydrodesulfurization test) by the above-mentionedmethod. Table 10 below shows the results.

TABLE 10 Exam- Exam- Exam- ple 1 Example 2 ple 3 Example 4 ple 5Hydrotreating ATC-10 ATC-11 ATC-12 ATC-13 ATC-14 catalyst No. Coatingamount of 4% 10% 20% 45% 30% titania* Specific surface 206 215 234 198232 area (m²/g) Pore volume 0.35 0.37 0.39 0.33 0.36 (ml/g) Poresharpness 62.1 67.6 73.2 62 70.2 degree (%) Relative 292 352 388 296 396desulfurization activity *Mass ratio of titania with respect to a totalon an oxide basis of titania and an alumina support

Examples 6 to 26

50 g of the titania-coated alumina support AT-2 was impregnated with thecatalytic component-containing aqueous solutions MS-2 to MS-22 as shownin Table 11 below and dried at 120° C. for 16 hours to givehydrotreating catalysts ATC-15 to ATC-35, respectively.

Each of the resultant hydrotreating catalysts ATC-15 to ATC-35 wasmeasured for its desulfurization activity (gas oil hydrodesulfurizationtest) by the above-mentioned method. Table 11 below shows the resultscollectively.

TABLE 11 Catalytic Relative component de- aqueous Hydrotreating Kind ofsulfurization solution No. catalyst No. saccharide activity Example 6MS-2 ATC-15 Sorbitol 396 Example 7 MS-3 ATC-16 Arabinose 396 Example 8MS-4 ATC-17 Xylose 358 Example 9 MS-5 ATC-18 Xylitol 375 Example 10 MS-6ATC-19 Ribose 393 Example 11 MS-7 ATC-20 Fructose 364 Example 12 MS-8ATC-21 Sorbose 365 Example 13 MS-9 ATC-22 Glucose 386 Example 14 MS-10ATC-23 Mannose 392 Example 15 MS-11 ATC-24 Galactose 377 Example 16MS-12 ATC-25 Mannitol 383 Example 17 MS-13 ATC-26 Dulcitol 362 Example18 MS-14 ATC-27 Sucrose 390 Example 19 MS-15 ATC-28 Lactose 393 Example20 MS-16 ATC-29 Maltose 381 Example 21 MS-17 ATC-30 Trehalose 376Example 22 MS-18 ATC-31 Maltitol 369 Example 23 MS-19 ATC-32 Isomerized392 sugar Example 24 MS-20 ATC-33 Raffinose 378 Example 25 MS-21 ATC-34Erythritol 391 Example 26 MS-22 ATC-35 Invert 370 sugar

When the titania-coated alumina support is caused to support molybdenum,cobalt, phosphorus, or the like so as to obtain a hydrotreatingcatalyst, hydrotreating catalysts of Examples each additionallysupporting a saccharide of sorbitol, arabinose, xylose, xylitol, ribose,fructose, sorbose, glucose, mannose, galactose, mannitol, dulcitol,sucrose, lactose, maltose, trehalose, maltitol, isomerized sugar,raffinose, erythritol, or invert sugar show extremely highdesulfurization activity. It was confirmed that each of the catalystscontaining those saccharides was able to improve a desulfurizationactivity by about 3- to 4-fold as compared to the ASC-2 catalyst free ofany saccharide.

Examples 27 and 28

Catalytic component-containing aqueous solutions MS-23 and MS-24 wereeach obtained in the same manner as in the catalyticcomponent-containing aqueous solution MS-2 except that, in thepreparation of the catalytic component-containing aqueous solution MS-2,respective saccharides shown in Table 12 below were used in respectiveamounts shown in the table in place of 3.6 g of sorbitol.

TABLE 12 Catalytic component aqueous Addition solution No. Kind ofsaccharide amount (g) Example 27 MS-23 Fructo-oligosaccharide 3.6Example 28 MS-24 Nigerose 7.1

Hydrotreating catalysts ATC-36 and 37 of Examples 27 and 28 wereobtained in the same manner as in Example 1 except that the catalyticcomponent-containing aqueous solutions MS-23 and 24 were used in placeof the catalytic component-containing aqueous solution MS-2 in Example1, respectively.

Each of the resultant hydrotreating catalysts ATC-36 and 37 wassubjected to a gas oil hydrodesulfurization test and measured for itsrelative desulfurization activity by the above-mentioned method. Table13 below shows the results.

TABLE 13 Relative Hydrotreating desulfurization catalyst No. Kind ofsaccharide activity Example 27 ATC-36 Fructo-oligosaccharide 242 Example28 ATC-37 Nigerose 258

Comparative Example 7

A catalytic component-containing aqueous solution MS-25 was obtained inthe same manner as in the above-mentioned catalytic component-containingaqueous solution MS-2 except that, in the preparation of the catalyticcomponent-containing aqueous solution MS-2, 7.1 g of starch were used inplace of 3.6 g of sorbitol.

In order to obtain a hydrotreating catalyst ATC-38 of ComparativeExample 7, the same operation as in Example 1 was carried out exceptthat the catalytic component-containing aqueous solution MS-25 was usedin place of the catalytic component-containing aqueous solution MS-2 inExample 1. However, when the titania-coated alumina support AT-1 wasimpregnated with the catalytic component-containing aqueous solutionMS-25, the catalytic component-containing aqueous solution did notpermeate the support. Hence, it was impossible to manufacture ahydrotreating catalyst ATC-38 impregnated with the catalyticcomponent-containing aqueous solution.

1. A manufacturing method for a hydrotreating catalyst for hydrocarbonoil, the method comprising: a titania coating step includingsimultaneously and continuously adding an aqueous solution of an acidiccompound containing titanium and an aqueous solution containing analkaline compound to a hydrosol containing an alumina hydrate particleat a temperature ranging from 10 to 100° C. and a pH ranging from 4.5 to6.5, and coating a surface of the alumina hydrate particle with atitanium hydroxide particle while keeping the pH constant to give atitania-coated alumina hydrate particle; a washing step of washing theresultant titania-coated alumina hydrate particle to remove acontaminating ion which coexists with the particle; a forming step offorming the washed titania-coated alumina hydrate particle afterdehydrating the particle so as to have a moisture content at which theparticle is formable; a first drying step of drying a shaped material ofa titanium-coated alumina hydrate particle obtained by the forming togive a titania-coated alumina support; an impregnating step ofimpregnating the resultant titania-coated alumina support with acatalytic component-containing aqueous solution containing at least onekind of periodic table group 6 metal compound, at least one kind ofperiodic table group 8-10 metal compound, and at least one kind ofphosphorus compound as catalytic components, and a saccharide; and asecond drying step of drying the titania-coated alumina supportimpregnated with the catalytic component-containing aqueous solution. 2.A manufacturing method for a hydrotreating catalyst for hydrocarbon oilaccording to claim 1, wherein the saccharide to be used in theimpregnating step comprises at least one kind of saccharide selectedfrom the group consisting of erythritol, arabinose, xylose, xylitol,ribose, fructose, sorbose, glucose, mannose, galactose, sorbitol,mannitol, invert sugar, dulcitol, sucrose, lactose, maltose, trehalose,maltitol, isomerized sugar, and raffinose.
 3. A manufacturing method fora hydrotreating catalyst for hydrocarbon oil according to claim 1,wherein the saccharide to be used in the impregnating step comprises atleast one kind of saccharide selected from the group consisting oferythritol, xylose, xylitol, sorbitol, mannitol, invert sugar, maltose,trehalose, maltitol, isomerized sugar, and raffinose.
 4. A manufacturingmethod for a hydrotreating catalyst according to any one of claims 1 to3, wherein a crystal system of the alumina hydrate particle comprisesboehmite, pseudoboehmite, and/or an alumina gel.
 5. A manufacturingmethod for a hydrotreating catalyst according to claim 1, wherein a poresharpness degree of the alumina hydrate particle after calcination at500° C. for 3 hours is 60% or more.
 6. A manufacturing method for ahydrotreating catalyst according to claim 1, wherein a temperaturecondition of the titania coating step is a temperature ranging from 15to 90° C.
 7. A manufacturing method for a hydrotreating catalyst forhydrocarbon oil according to claim 1, wherein an operation of thetitania coating step is carried out under the following conditions for(a) pH and (b) coating time: (a) pH: within a pH variation range of ±0.5with respect to a pH to be determined with the following equation (1):pH=6.0−0.03×T  Equation (1) in the equation (1), T represents a ratio(mass %) of titania with respect to a whole of the titania-coatedalumina hydrate particle (oxide basis); and (b) coating time: within arange of 5 minutes to 5 hours.
 8. A manufacturing method for ahydrotreating catalyst for hydrocarbon oil according to claim 1, whereinan amount of titanium hydroxide with which the alumina hydrate particleis coated falls within a range of 5 to 40% by mass with respect to atotal amount on an oxide basis.
 9. A manufacturing method for ahydrotreating catalyst for hydrocarbon oil according to claim 1, whereinan aging time in the impregnating step falls within a range of 10minutes to 24 hours.
 10. A manufacturing method for a hydrotreatingcatalyst for hydrocarbon oil according to claim 1, wherein the periodictable group 6 metal to be used in the impregnating step comprisesmolybdenum and the periodic table group 8-10 metal comprises cobaltand/or nickel.
 11. A manufacturing method for a hydrotreating catalystfor hydrocarbon oil according to claim 1, wherein an addition amount ofthe saccharide to be used in the impregnating step falls within a rangeof 1 to 20% by mass with respect to a total amount on an oxide basis ofthe support and the catalytic components.
 12. A hydrotreating catalystfor hydrocarbon oil, which is manufactured by the manufacturing methodfor a hydrotreating catalyst for hydrocarbon oil according to claim 1.13. A hydrotreating catalyst for hydrocarbon oil according to claim 12,wherein the catalyst has supported thereon a periodic table group 6metal compound, a periodic table group 8-10 metal compound, a phosphoruscompound, and a saccharide.
 14. A hydrotreating catalyst for hydrocarbonoil according to claim 12 or 13, wherein a repetition length of acrystal lattice plane of titania in the titania-coated alumina supportis 50 Å or less.
 15. A hydrotreating catalyst for hydrocarbon oilaccording to claim 12, wherein a pore sharpness degree of thetitania-coated alumina support is 60% or more.
 16. A hydrotreatingcatalyst for hydrocarbon oil according to claim 12, wherein a porevolume of the titania-coated alumina support is 0.36 to 1.10 ml/g.
 17. Ahydrotreating catalyst for hydrocarbon oil according to claim 12,wherein a specific surface area of the titania-coated alumina support is200 m²/g or more.
 18. A hydrotreating catalyst for hydrocarbon oilaccording to claim 12, wherein a compact bulk density (CBD) of thecatalyst is 0.5 to 1.1 g/ml.
 19. A hydrodesulfurization treatment methodfor hydrocarbon oil, comprising using a hydrotreating catalyst forhydrocarbon oil manufactured by the manufacturing method for ahydrotreating catalyst for hydrocarbon oil according to claim 1.